Gas seal for rotatable cartridge drum



Dec. 8, 1964 J. w. TREAT ETAL GAS Filed July 27, 1962 SEAL FOR ROTATABLECARTRIDGE DRUM 2 Sheets-Sheet l fiow X2 IN VEN TORS Jnhn 'LLL. Treat.J'r. BY RCflJBIi L. Hall.

-R F. Robinson Dec. 8, 1964 J. w. TREAT ETAL GAS SEAL FOR ROTATABLECARTRIDGE DRUM 2 Sheets-Sheet 2 Filed July 27, 1962 INVENTORS, Jul-m.ILL- Tr'e at Jr- By R n'hali .L-Ha1l. R F. Robinson. 2 4 @mzb- 9mm @bp zUnited States Patent Marblehead, Mass, and Robert F. Robinson, Monroe,

Conn., assignors, by mesne assignments, to the United States of Americaas represented by the Secretary of the Army Fiied July 27, 1962, Ser.No. 213,064

7 Claims. (Cl. 42--59) This invention relates to a gas seal and moreparticularity to an obturating seal for use in revolver type guns inwhich cartridges are chambered in circumferentially spaced bores in arevolving drum for feeding into a gun barrel or barrels.

It is usual in the revolver type gun to have an obturating seal slidablymounted in each bore. Each seal moves forward upon firing of a cartridgetherein to seal between the end of the bore and the breech end of thebarrel.

It is also usual to have a sealing aid between the sealing face of theobturating seal and the breech face of the barrel of the gun. These aidsconsist of many forms such as grooves, rings, etc.

Additional features desirable in the design of obturating seals are to:

(a) Reduce heat transfer into the drum;

(b) Reduce impact between the seal and the end of the barrel, and

(0) Increase barrel life.

The present invention is designed to accomplish the aforesaid featuresby providing a ring which floats in a recess in the drum face. The ringis forced against the barrel face by gases, which are ported into achamber at the rear of the seal.

It is a primary object of this invention to reduce the heat transferinto the revolving drum of a revolver type gun by reducing the leakageof gas between the face of the seal and the end of the barrel andbetween the outside diameter of the seal and the inside diameter of thedrum counterbore, by breaking up carbon and metallic deposits on theface of the barrel against which the seal seats, and by reducing thelength of travel of high velocity gases leaking between the face of thebarrel and the face of the seal which seats against it. 7

It is another object of this invention to reduce the impact forcebetween the seal and the end of the barrel by the spring effect of anobturating ring, by the effect of the long taper of the inside diameterof the seal and by the drag of a primary seal located between theoutside diameter of the seal and drum counterbore.

A further object of the invention is to provide increased barrel life bythe self alignment feature of the spherical segment which provides fullsealing surfaces between the body of the seal and end of the barrel,thereby decreasing leakage and the erosion which results therefrom andby decreased impact'of the seal and barrel which eliminates surfacecracks on the end of the barrel.

Thevspecific nature of the invention as well as other objects andadvantages thereof, will clearly appear from a description of apreferred embodiment as; shown in the accompanying drawings in which:

FIGURE 1 is a fragmented sectional view taken through a cartridge drumof a revolver type gun and showing the seal of the invention;

FIGURE 2 is an axial section, partly in elevation, of an obturating sealin assembled relation;

FIGURE 3 is a partial section showing the primary sealing means,

FIGURE 4 is a detail section on an enlarged scale of the primary sealingmeans and its relation with the inside diameter of the obturating seal;

3,159,938 Patented Dec. 8, 1964 ice FIGURE 5 is a similar view showingthe primary sealin g means upon initial pressurization;

FIGURE 6 is a detail section of the sealing ring having an O-ring seal;

FIGURE 7 is a detail section of a modified form of sealing ring having agrooved face;

FIGURE 8 is a view in section showing a sealing ring in its entirety andhaving a smooth face;

FIGURE 9 is a partial section showing a sealing ring having a roundedface, and;

FIGURE 10 is a side view of one of the primary sealing members.

Referring to the drawings, reference character 1 (FIG- URE 1) representsa portion of a cartridge drum of a revolving type gun and shows one here2 for chambering a cartridge therein.

Drum l is mounted on an axial shaft 3. Bore 2 is counterbored as at 4 toreceive a cylindrical seal member indicated generally by 5. Seal 5 isslidably mounted in counterbore 4.

A cartridge 6 is shown in bore 2 in FIGURE 1.

Seal 5 is cylindrical and has a central bore 7 therethrough. Bore 7 isprovided with a lon rearward tapered inside diameter as at 8.

Seal 5 is provided at its peripheral surface near the rear with anannular groove 9 forreceiving a primary sealing means which comprises apair of split rings 10. Rings 10 are square in cross section as bestseen in FIG- URES 4 and 5 for a purpose to be apparent later.

Seal 5, as illustrated, is provided with an enlarged head portion itwhich is counterbored to form an annular recess having a concaverearward wall. An inwardly extending annular flange 13 provides meansfor retaining a gasket.

An obturating ring indicated generally by 14 floats in recess 12.

Ring 14 is provided with an axial bore 15 and a rearward reduced portion16.

Reduced portion 116 is convex on its rearward face as at 17 to mate withthe concave rearward wall of recess 12. This wall and face 17 both formsegments of a circle for a smooth sliding fit.

FIGURE 6 depicts a modified form of obturating ring.

In this form the obturating ring is shown used with an O-ring seal 18.

In order to secure the O-ring, an annular channel 19 is provided in theinner peripheral surface of the seal 5.

An annular flange 29 is provided on the outer peripheral surface of theobturating ring 14 for retaining obturating ring 14 in the recess 12.

FIGURES 1-6 and 8 show obturating sealing ring 14 having a flat forwardface.

In FIGURE 7, there is shown a ring having a grooved face. Circulargrooves 21 are provided in the forward face of the ring 14 for cleaningcarbon from the breech face of barrel B.

Another modified face for an obturating ring is shown in FIGURE 9, inwhich the face is rounded as at 22.

The action of the seal 5 is as follows, and is best demonstrated byFIGURES 1 and 6 in which the principal features are shown. 7

Arrow A indicates the direction of the guns muzzle, B being the breechend of the gun barrel and the nose of projectile P is in its positionfor firing.

The seal is assembled into the drum with the concave recess 12 in thedirection of barrel B and its rear end in the direction of the base ofcartridge 5 (see FIGURE 1). Lineal relationships are such to the restof'the cartridge that the projectile P protrudes into the seal 5 withthe obturating band 0 position to the left side of the seal 5. As drum 1indexes into battery position, the seal 5 is cammed to the left by thespace relationships provided in the overall gun design. When cartridge 6is fired, the projectile is forced out of its case and starts itsmovement through the inside diameter of the seal. The long introductorytaper 8 of seal is so dimensioned that the interference fit between theobturating ring 14 and the inside diameter of seal 5 does not occuruntil projectile P is well into taper 8.

Prior to reaching this point, chamber pressure is high enough to producea longitudinal pressure drop across the seal 5 which forces the seal 5to the right, bringing the obturating ring 14 into contact with the endof barrel B. While this action is occurring, gas flows under primaryseals 10, resulting in a sealing action by forcing seals 19 outwardlyagainst the counterbore 4 of drum 1 (see FIGURE 4) and against othersealing surfaces to form an effective gas barrier. The misalignmentexisting between the centerline of the seal 5 and the centerline of bandB, plus other conditions due to the lack of squareness of sealingsurfaces with this centerline are overcome by the action of theobturating rings rounded surface 17 and the concave recess 12 of seal 5which automatically aligns itself to overcome these misalignmentfeatures. Misalignment referred to is that due to manufacturingtolerances, differential expansions due to temperature differentials inparts, and springing of gun structure due to setback loads actingthereon.

Impact, which would normally be experienced with a right circularcylinder acting as a seal, and which is normally present due to thekinetic energy in this seal built up during its travel to overcomeclearance between it and the barrel B, is reduced by the dragging actionof primary seals 1f), the spring action of obturating ring 14 which actsin the same manner as a Belleville washer, and the reduced internal dragbetween the obturating ring 14 on projectile P and the inside diameter7, 8 on projectile P.

In addition, the tapered bore 8 of seal 5 introduces this drag at a timewhen it can offer frictional damping characteristics.

As the annular grooves 21 in the face of obturating ring come in contactwith the end of barrel B, any carbon or metallic deposits are broken up,thereby allowing a more satisfactory sealing action to occur.

During gas pressurization in the sealed area, leakage is reduced to aminimum by the action of the primary seals lit, and by the action of theannular grooves 21 in the face of obturating ring 14. This reduces heatin put by decreasing both the quantity of gas and the length of travelof high velocity gases. As the empty cartridge case 6 is indexed out ofbattery position the annular grooves 21 provide a wiping action whichserves to clean the end of the barrel.

The action of the obturating ring 14 with relation to the seal recess 12may be further demonstrated in FIG- URE 6 where a represents the initialcontact area (when parts are new) and b represents the direction contactincreases as the members defiect under a load and as parts wear.

The purpose of rings 10, which are similar to split piston rings (seeFIGURE is to provide the primary means of confining the gas that escapesaround the outside diameter of seal 5. Where clearances are large theyare particularly effective because it requires a very high pressure tocause the ring 14 to obturate.

FIGURES 4 and 5 illustrate the action of the primary seals 10.

It will be seen from these figures that the rings 1t are square in crosssection to provide sharp edges to aid in removing accumulated carbonwhich would collect between the outside diameter of the rings and thecounterbore 4 of drum 1 and interfere with eificient obturation.

The rings 10 act against three surfaces in performing their sealingaction as follows: (See FIGURE 5). (1) The axial pressure drop forcesring indicated by Y against ring indicated by Y and as the splits 23(see FIGURE 10) are installed 180 apart, direct axial leakage throughthe rings 10 is prevented. (2) Ring Y is forced against the edge ofgroove 9 preventing leakage in a radial direction past ring Y exceptthrough a split 23 in the ring. (3) The radial outward pressure dropforces both rings Y and Y against the bore of drum 1, causing the ringsto fit tightly against the inside diameter of drum 1. (See FIGURE 4.)

This action occurs after the void between the rings 10 and the length ofthe diameter of the groove is pressurized.

The initial pressurization, though transient in nature, is shown in FIG.5. As combustion gas reaches rings 10, it forces both rings 10 inward asthe void between the rings is not initially pressurized.

Also, the pressure drop across ring Y will be greater than that across YThese drops may or may not be great enough to prevent rings 10 fromrecovering enough to act in the manner shown in FIG. 4. Also leakagepast the split 23 in ring Y may be great enough to cause some distortionat split 23 in that ring.

The rings 10 are slightly oversize. Their cross section is such toprevent permanent deformation when they are installed in grooves 9.

Long taper 8 permits proper alignment of the obturating band 0 (seeFIG. 1) as it enters the inner diameter of seal 5. This taper has aneffect upon the impact force of the obturating ring 14 face as it isdriven against the end of barrel B. This impact is due to accelerationof the seal 5 mass through its clearance by 1) the axial pressure drop,(2) the drag force produced by the swaging action of the obturating band0 passing through the bore 8, 7, (3) the axial clearance between theface of obturating ring 14 and barrel B, and (4) the point ofapplication of the swaging force. The use of a long introductory taperreduces the impact force by allowing gas pressure to force seal 5 andobturating ring 14 against barrel B prior to the time of swaging action,and also to reduce peak pressure produced between the face of obturatingring 14 and barrel face of B by reducing the swaging force.

Variations and modifications may be effected without departing from thescope of the novel concept of the present invention as set forth in theappended claims.

What is claimed is:

1. In combination with a rotatable cartridge drum for feeding cartridgesinto a gun barrel, there being at least one axially spaced bore throughsaid drum for chambering a cartridge, said bore having a forwardlydisposed counterbore, a gas seal for preventing leakage of combustiongases between said drum and said barrel comprising, a cylindrical memberhaving an axial bore therethrough, said cylindrical member beingslidably mounted in said counterbore in said drum, said axial borehaving an annular recess in its forward portion thereof, said recesshaving a concave rearward wall, seal means between the outside surfaceof said cylindrical member and the inside surface of said counterborecarried by said cylindrical member, a ringlike obturating member betweensaid couunterbore and said barrel movably mounted in said recess, saidringlike member having a rearward convex surface to engage said concaverearward wall and a forward face to engage said barrel and means sealingbetween the outside surface of said ringlike obturating member and theinside surface of said recess in said cylindrical member said firstmentioned seal means comprising an annular groove disposed in the outerperipheral surface of said cylindrical member and a pair of splitcircular rings in side-by-side relation in said groove and adapted toexpand and engage the inside surface of said counterbore, said splitrings being angularly positioned with respect to each other.

2. In a device as set forth in claim 1 wherein said split rings have anoutside diameter slightly larger than the outside diameter of saidcylindrical member.

3. In a device as set forth in claim 1 wherein said split rings have asquare cross section.

4. A device as set forth in claim 1 wherein said concave wall in saidrecess defines'a segment of a circle.

5. A device as set forth in claim 1 wherein the barrel engaging face ofsaid ringlike member is rounded.

7. In combination with a rotatable cartridge drum for feeding cartridgesinto a barrel, there being at least one axially spaced bore through saiddrum for chambering a cartridge, said bore having a forwardly disposedcounterbore, a gas seal for preventing leakage of combustion gasesbetween said drum and said barrel comprising:

a cylindrical member having an axial bore therethrough,

said cyclindrical member being slidably mounted in said counterbore insaid drum,

said axial bore having an annular recess in its forward portion thereof,

said recess having a concave rearward wall and an annular grooveforwardly of said rearward wall, 7 seal means between the outsidesurface of said cylindrical member and the inside wall ofsaid'counterbore carried by said cylindrical member,

a ringlike, obturating member movably mounted in said annular recess,said obturating member having a convex surface to engage said concavewall and aforward surface to engage the rear surface of said barrel,

said obturating member having an outwardly extending annular flange onthe outer surface thereof adjacent said annular groove, an O-ringdisposed in said annular groove outwardly of and adjacent said annularflange.

References Cited by the Examiner UNITED STATES PATENTS BENJAMIN A.BORCHELT, Primary Examiner.

SAMUEL FEINBERG, Examiner.

1. IN COMBINATION WITH A ROTABLE CARTRIDGE DRUM FOR FEEDING CARTRIDGESINTO A GUN BARREL, THERE BEING AT LEAST ONE AXIALLY SPACED BORE THROUGHSAID DRUM FOR CHAMBERING A CARTRIDGE, SAID BORE HAVING A FORWARDLYDISPOSED COUNTERBORE, A GAS SEAL FOR PREVENTING LEAKAGE OF COMBUSTIONGASES BETWEEN SAID DRUM AND SAID BARREL COMPRISING, A CYLINDRICAL MEMBERHAVING AN AXIAL BORE THERETHROUGH, SAID CYLINDRICAL MEMBER BEINGSLIDABLY MOUNTED IN SAID COUNTERBORE IN SAID DRUM, SAID AXIAL BOREHAVING AN ANNULAR RECESS IN ITS FORWARD PORTION THEREOF, SAID RECESSHAVING A CONCAVE REARWARD WALL, SEAL MEANS BETWEEN THE OUTSIDE SURFACEOF SAID CYLINDRICAL MEMBER AND THE INSIDE SURFACE OF SAID COUNTERBORECARRIED BY SAID CYLINDRICAL MEMBER, A RINGLIKE OBTURATING MEMBER BETWEENSAID COUNTERBORE AND SAID BARREL MOVABLY MOUNTED IN SAID RECESS, SAIDRINGLIKE MEMBER HAVING A REARWARD CONVEX SURFACE TO ENGAGE SAID CONCAVEREARWARD WALL AND A FORWARD FACE TO ENGAGE SAID BARREL AND MEANS SEALINGBETWEEN THE OUTSIDE SURFACE OF SAID RINGLIKE OBTURATING MEMBER AND THEINSIDE SURFACE OF SAID RECESS IN SAID CYLINDRICAL MEMBER SAID FIRSTMENTIONED SEAL MEANS COMPRISING AN ANNULAR GROOVE DISPOSED IN THE OUTERPERIPHERAL SURFACE OF SAID CYLINDRICAL MEMBER AND A PAIR OF SPLITCIRCULAR RINGS IN SIDE-BY-SIDE RELATION IN SAID GROOVE AND ADAPTED TOEXPAND AND ENGAGE THE INSIDE SURFACE OF SAID COUNTERBORE, SAID SPLITRINGS BEING ANGULARLY POSITIONED WITH RESPECT TO EACH OTHER.